While left-handed starting pitcher Eduardo Rodriguez was initially thought to be on his way back from the 15-day disabled list and ready to join the Boston Red Sox starting rotation in short time, it appears as if the 23-year-old has suffered another setback in his recovery.

Rodriguez dealing with knee soreness

Rodriguez, who was placed on the disabled list after sustaining a patellar subluxation in his right knee during fielding practice in early spring training, has yet to throw with the Red Sox in 2016, and that fact will remain true for at least another week as he is dealing with soreness in that same knee.

Originally slated to make his third rehab start with Triple-A Pawtucket on Thursday, Rodriguez has been scratched from that start with his disabled list stint set to expire on May 28, 30 days from when he made his first rehab start.

Once the 30-day period has finished, players can either be called up to the big league squad or placed on the disabled list for another 15 days, putting manager John Farrell in a predicament should Rodriguez's knee soreness persist.

Is Rodriguez's velocity declining?

Rodriguez broke out in his rookie season of 2015, introducing a consistent 94-mph fastball which opposing batters hit for an average of just .263 against and a wicked changeup which opposing batters fared just .185 against.

The Venezuelan entered the 2016 campaign with expectations of him complementing fellow left-hander David Price in upper-middle echelon of the rotation, creating a reliable 1-2 lefty punch after a 10-6 season in which he accumulated an ERA of 3.85, a WHIP of 1.29, and a BAA of .255.

However, Rodriguez has been hampered considerably by the initial injury that landed him on the DL. Unable to push his full weight on the injured knee while dealing with a lack of right quad strength, he has lost velocity on his fastball since last season, as evidenced by his previous four rehab starts.

In those starts, Rodriguez has amounted a 4.29 ERA in 21 innings, allowing half as many home runs (five) as strikeouts (10) while walking five batters.